Influence of patterned sapphire substrates with different symmetry on the light output power of InGaN-based LEDs

Abstract

This paper aims to investigate the light output power (LOP) of InGaN-based light-emitting diodes (LEDs) grown on patterned sapphire substrates (PSSs) with different symmetry. The GaN epitaxial layers grown on the hexagonal lattice arrangement PSS (HLAPSS) have a lower compressive strain than the ones grown on the square lattice arrangement PSS (SLAPSS). The quantum-confined Stark effect (QCSE) is also affected by the residual compressive strain. Based on the experimentally measured data and the ray tracing simulation results, the InGaN-based LED with the HLAPSS has a higher LOP than the one with the SLAPSS due to the weaker QCSE within multiple-quantum wells (MQWs).

The morphology evolution of selective area wet etched commercial patterned sapphire substrates

“…Therefore, the change of slant angle may be attributed to the limitation effect of the SiO 2 mask. It is well known that the slant angle of patterned sapphire substrate plays an important role in enhancing the LEE of LEDs [18,19]. The process of controlling slant angle by etching time can be used to optimize the slant angle of PSS.…”

Application of patterned sapphire substrate for III-nitride light-emitting diodes

“…Two types of PSS symmetry including square lattice and hexagonal lattice arrangement were fabricated. 150 Owing to the higher symmetry of PSS with hexagonal lattice arrangement (HLAPSS), LED grown on HLAPSS shows relaxed compressive strain more than that on PSS with square lattice arrangement (SLAPSS). Besides, compared to SLAPSS, HLAPSS results in weaker QCSE in MQWs, which alleviates the efficiency droop and leads to higher LOP of LEDs.…”

Growth of GaN on Patterned Sapphire Substrate with High-Index Facets

“…[1][2][3][4] PSSs with various structural parameters including spacing, slanted angle, shape, height, density, and symmetry have been studied in recent years for further improvements of the LED performance. [4][5][6][7][8][9] PSS can be fabricated either by dry-etching or wet-etching method. In wet etching, sapphire substrate covered with disk-shape SiO 2 hard mask is usually etched with a mix solution of H 3 PO 4 and H 2 SO 4.…”